Non-volatile optical switch based on Sb₂Se₃-loaded three-mode interference

In this Letter, we propose a non-volatile switch based on multimode interference in an Sb₂Se₃-loaded waveguide. By implementing low-loss phase control within a multimode interference coupler, this design effectively manages the self-imaging phase shift length during a single phase change cycle. The fabricated multiplexed optical switch exhibits impressive performance characteristics, including a low insertion loss of ∼ 1.5 dB, a compact length of ∼35 μm, and minimal cross talk below -6 dB over a 35 nm bandwidth for both the amorphous and crystalline states. The ability to reconfigure light routing via Sb₂Se₃ phase transitions opens new avenues for optical field-programmable gate arrays and high-density photonic processors.